It is common practice for therapists, physicians, athletes, and other individuals to utilize various treatment and therapy devices to promote muscle training, conditioning, and growth. In addition, devices often referred to as Transcutaneous Nerve Stimulation (“TENS”) units are employed to manage pain and discomfort through blocking of the nerve signal from the area of discomfort to the brain. With muscle stimulation and nerve stimulation, a device is programmed to output various levels of electrical pulses. The frequency, duration, pulse width, and intensity of the output signal control the directed treatment goals.
With regard to muscle stimulation, there are a myriad of uses for these electro-stimulation devices. Treatment categories can generally be divided between muscle fitness, muscle aesthetic, sport training, pain management, muscle rehabilitation, and vascular therapy. Each category is directed to a different stimulation goal. With muscle fitness, the goal is generally to restore, improve, or maintain a good physical condition by building muscle, muscle tone, volume, trophism, metabolism, and the like. With muscle aesthetic goals, the stimulator is often utilized on muscles in order to shape, firm, refine, increase elasticity, and increase caloric expenditure. Sports-minded individuals may use the device to increase muscular endurance and strength, increase blood flow to promote active recovery, and the like. When focus is on muscle rehabilitation, muscular stimulation is needed to restore or otherwise redevelop a convalescent muscle. Under the vascular category of treatment programs, the goal is to improve blood circulation in the stimulated area to minimize circulatory problems, fatigue, lack of oxygenation, swelling, and other related problems. In pain management applications, electro-stimulation devices are used primarily to alleviate muscle pain or other discomfort.
Regardless of the unique goal-dependent outputs of the device, electro-stimulation works under a principle of voluntary muscle contraction. When individuals contract a muscle, the brain sends the information to the muscle via the motor nerve. With electro-stimulation, a suitable electric current acts directly on the nerve by means of electrical impulses that reproduce the natural physiological phenomenon. These electrical impulses are applied to the user through attached electrodes. The electrodes are typically adhesively attached to the person or person's clothing. With electro-stimulation a patient or user can achieve intensive muscular work without mental or cardiac fatigue, thus reducing joint and tendon constraints. U.S. Pat. No. 6,324,432, commonly assigned with the present application to Compex SA, discloses an electrical neuromuscular stimulator for measuring muscle responses to electrical stimulation pulses, and U.S. Patent Application Publication No. 2003/0074037 discloses an electrical nerve stimulation device. U.S. Pat. No. 6,324,432 and U.S. Patent Application Publication No. 2003/0074037 are incorporated by reference herein in their entireties.
However, conventional electro-stimulation devices, while useful in achieving intensive muscular work for a target or generalized muscle set, are not capable of self-adjusting for various muscle groups. Conventional devices are also not capable of automatically adjusting for various users; even though two patients may be seeking the same general therapeutic or training effects, each may be at a different fitness or recovery stage. Further, conventional electro-stimulation devices are not generally able to self-adjust for detected physiological traits of a particular user.
Conventional devices also frequently require application and supervision by a trained medical professional to prevent muscle over-stimulation, fatigue, or, in extreme situations, injury. Additionally, electro-stimulation treatment delivered by conventional devices is typically less efficient because theses devices are unable to consider or account for muscle feedback. As a muscle is stimulated, it may react or respond in a manner for which adjustment of the stimulation is appropriate. For example, a fatigue level experienced by a muscle varies and generally accelerates as treatment progresses. Fatigue levels experienced and the acceleration of fatigue will be different for each user and each target muscle or group and must be carefully monitored to increase the efficiency of electro-stimulation in sports applications.
Monitoring muscle response and feedback directly is difficult and impractical in most treatment situations as such monitoring is most effectively accomplished by subcutaneous sensors. While transcutaneous applications of accelerometers or other devices are known, electro-stimulation devices presently available cannot accurately and actively self-adjust a treatment session based on detected feedback. Further, the measurements are often inaccurate because of interference from other active but non-target muscles.
U.S. Pat. No. 4,817,628 discloses a system and method for evaluating neurological function controlling muscular movements. The system generally includes an accelerometer sensor, a stimulus electrode assembly, and a portable device to which the sensor and electrode assembly are connected. The sensor measures the magnitude of the (stimulus evoked) movement of a body part of the subject along at least one axis of three-dimensional space.
U.S. Pat. No. 6,282,448 discloses a self-applied and self-adjusting device and method for prevention of deep vein thrombosis with movement detection. An accelerometer can detect motion and keep the device operating until motion is generated and/or turn the device off when motion is detected, generated by the device or user.
U.S. Patent Application Publication No. 2002/0165590 discloses an apparatus for stimulating a muscle of a subject. An accelerometer may be employed that is positioned adjacent a muscle of the subject that is being stimulated. This meter then tracks the magnitude of the shivers generated in the muscle. If this magnitude exceeds a predetermined level, the apparatus is notified and may be adjusted or shut off.
Additionally, Tarata et al. discuss general approaches used to monitor muscle fatigue in “The Accelerometer MMG Measurement Approach, in Monitoring the Muscular Fatigue,” from the MEASUREMENT SCIENCE REVIEW, Vol. 1, No. 1, 2001, and in “Mechanomyography versus Electromyography, in monitoring the muscular fatigue,” from BIOMEDICAL ENGINEERING ONLINE, published Feb. 11, 2003. McLean provides a mechanomyography summary in a subject message “MMG summary” posted to a Biomechanics and Movement Science listserver on Mar. 30, 1998. The above articles are incorporated by reference herein in their entireties.
The need remains, however, for an electrical muscle stimulation device and corresponding electrode system that substantially addresses the innate drawbacks of conventional devices and systems.